I was about to use the encryptfs procedure to migrate my existing home folder and discovered that the process needs 2.5x the size of home to complete. I have 258GB in my home, but only 430GB free. Is there a way that I can encrypt home without reinstalling?

yes, but you need to temporarily store some of the home data to another partition and then encrypt the home partition (which is less used). However, you should maybe also think about not encrypting the whole home directory, but only important private data.
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Michael KJan 13 '12 at 13:55

What happens if I move "documents," then encrypt, then copy documents back after encryption? will this work?
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KendorJan 14 '12 at 1:26

yes of course, it is as if you would store new data on your home drive.
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Michael KJan 16 '12 at 7:07